/*
* Copyright 2008 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package com.google.gwt.user.client.impl;
import com.google.gwt.user.client.DOM;
import com.google.gwt.user.client.Element;
import com.google.gwt.user.client.Window.Location;
/**
* History implementation for IE6 and IE7, which do not support the onhashchange
* event, and for which {@link HistoryImplTimer} will not work either.
*/
class HistoryImplIE6 extends HistoryImpl {
/**
* Sanitizes an untrusted string to be used in an HTML context. NOTE: This
* method of escaping strings should only be used on Internet Explorer.
*
* @param maybeHtml untrusted string that may contain html
* @return sanitized string
*/
private static String escapeHtml(String maybeHtml) {
final Element div = DOM.createDiv();
DOM.setInnerText(div, maybeHtml);
return DOM.getInnerHTML(div);
}
private static native Element findHistoryFrame() /*-{
return $doc.getElementById('__gwt_historyFrame');
}-*/;
/**
* For IE6, reading from $wnd.location.hash drops part of the fragment if the
* fragment contains a '?'. To avoid this bug, we use location.href instead.
*/
private static native String getLocationHash() /*-{
var href = $wnd.location.href;
var hashLoc = href.lastIndexOf("#");
return (hashLoc > 0) ? href.substring(hashLoc) : "";
}-*/;
private static native Element getTokenElement(Element historyFrame) /*-{
// Initialize the history iframe. If '__gwt_historyToken' already exists, then
// we're probably backing into the app, so _don't_ set the iframe's location.
if (historyFrame.contentWindow) {
var doc = historyFrame.contentWindow.document;
return doc.getElementById('__gwt_historyToken');
}
}-*/;
protected Element historyFrame;
private boolean reloadedWindow;
@Override
public boolean init() {
historyFrame = findHistoryFrame();
if (historyFrame == null) {
return false;
}
initHistoryToken();
// Initialize the history iframe. If a token element already exists, then
// we're probably backing into the app, so _don't_ create a new item.
Element tokenElement = getTokenElement(historyFrame);
if (tokenElement != null) {
setToken(getTokenElementContent(tokenElement));
} else {
navigateFrame(getToken());
}
injectGlobalHandler();
initUrlCheckTimer();
return true;
}
@Override
protected final void nativeUpdate(String historyToken) {
/*
* Must update the location hash since it isn't already correct.
*/
updateHash(historyToken);
navigateFrame(historyToken);
}
@Override
protected final void nativeUpdateOnEvent(String historyToken) {
updateHash(historyToken);
}
private native String getTokenElementContent(Element tokenElement) /*-{
return tokenElement.innerText;
}-*/;
/**
* The URL check timer sometimes reloads the window to work around an IE bug.
* However, the user might cancel the page navigation, resulting in a mismatch
* between the current history token and the URL hash value.
*
* @return true if a canceled window reload was handled
*/
private boolean handleWindowReloadCanceled() {
if (reloadedWindow) {
reloadedWindow = false;
updateHash(getToken());
return true;
}
return false;
}
private native void initHistoryToken() /*-{
// Assume an empty token.
var token = '';
// Get the initial token from the url's hash component.
var hash = @com.google.gwt.user.client.impl.HistoryImplIE6::getLocationHash()();
if (hash.length > 0) {
try {
token = this.@com.google.gwt.user.client.impl.HistoryImpl::decodeFragment(Ljava/lang/String;)(hash.substring(1));
} catch (e) {
// Clear the bad hash (this can't have been a valid token).
$wnd.location.hash = '';
}
}
@com.google.gwt.user.client.impl.HistoryImpl::setToken(Ljava/lang/String;)(token);
}-*/;
private native void initUrlCheckTimer() /*-{
// This is the URL check timer. It detects when an unexpected change
// occurs in the document's URL (e.g. when the user enters one manually
// or selects a 'favorite', but only the #hash part changes). When this
// occurs, we _must_ reload the page. This is because IE has a really
// nasty bug that totally mangles its history stack and causes the location
// bar in the UI to stop working under these circumstances.
var historyImplRef = this;
var urlChecker = $entry(function() {
$wnd.setTimeout(urlChecker, 250);
// Reset the hash if the user cancels a window reload triggered by the
// urlChecker.
if (historyImplRef.@com.google.gwt.user.client.impl.HistoryImplIE6::handleWindowReloadCanceled()()) {
return;
}
var hash = @com.google.gwt.user.client.impl.HistoryImplIE6::getLocationHash()();
if (hash.length > 0) {
var token = '';
try {
token = historyImplRef.@com.google.gwt.user.client.impl.HistoryImpl::decodeFragment(Ljava/lang/String;)(hash.substring(1));
} catch (e) {
// If there's a bad hash, always reload. This could only happen if
// if someone entered or linked to a bad url.
historyImplRef.@com.google.gwt.user.client.impl.HistoryImplIE6::reloadWindow()();
}
var historyToken = @com.google.gwt.user.client.impl.HistoryImpl::getToken()();
if (historyToken && (token != historyToken)) {
historyImplRef.@com.google.gwt.user.client.impl.HistoryImplIE6::reloadWindow()();
}
}
});
urlChecker();
}-*/;
private native void injectGlobalHandler() /*-{
var historyImplRef = this;
var oldOnLoad = $wnd.__gwt_onHistoryLoad;
$wnd.__gwt_onHistoryLoad = $entry(function(token) {
historyImplRef.@com.google.gwt.user.client.impl.HistoryImpl::newItemOnEvent(Ljava/lang/String;)(token);
if (oldOnLoad) {
oldOnLoad(token);
}
});
}-*/;
private native void navigateFrame(String token) /*-{
var escaped = @com.google.gwt.user.client.impl.HistoryImplIE6::escapeHtml(Ljava/lang/String;)(token);
var doc = this.@com.google.gwt.user.client.impl.HistoryImplIE6::historyFrame.contentWindow.document;
doc.open();
doc.write('<html><body onload="if(parent.__gwt_onHistoryLoad)parent.__gwt_onHistoryLoad(__gwt_historyToken.innerText)"><div id="__gwt_historyToken">' + escaped + '</div></body></html>');
doc.close();
}-*/;
private void reloadWindow() {
reloadedWindow = true;
Location.reload();
}
private native void updateHash(String token) /*-{
$wnd.location.hash = this.@com.google.gwt.user.client.impl.HistoryImpl::encodeFragment(Ljava/lang/String;)(token);
}-*/;
}